Flexible needle

ABSTRACT

An endoscopic instrument comprises a first flexible insertion member sized for insertion through a body lumen to a target site and a needle coupled to the insertion member for penetration of tissue, the needle including a plurality of flexibility enhancing grooves formed therein along at least a first portion of the length of the needle.

BACKGROUND

Conventional sclerotherapy catheters include needles which areextendable and retractable beyond distal ends thereof. Such a catheteris typically inserted through an endoscope located at a desired positionwithin the body. The catheter is pushed distally through the endoscopeuntil a distal end of the catheter extends beyond a distal end of theendoscope. The needle is then extended from the catheter and insertedinto the target tissue and a sclerosing agent is administered thereto tocause the target tissue to thicken or harden.

The needles typically utilized in conjunction with such sclerotherapycatheters are rigid, which hinders maneuverability of the catheterswithin endoscopes. Also, these needles often have a length of at least 1cm to allow them to successfully puncture tissue and administer asclerosing agent. The rigidity and length of the needles presentdifficulties in attempting to guide the sclerotherapy catheter throughan endoscope and/or through a body lumen. That is, if advancing thecatheter through an endoscope requires bending the sclerotherapycatheter around a tight radius, the needle may be exposed, puncturingthe catheter and/or the endoscope. In some cases, the needle may preventthe sclerotherapy catheter from moving past the tight radius.

SUMMARY OF THE INVENTION

The present invention is directed to an endoscopic instrument comprisinga first flexible insertion member sized for insertion through a bodylumen to a target site and a needle coupled to the insertion member forpenetration of tissue, the needle including a plurality of flexibilityenhancing grooves formed therein along at least a first portion of thelength of the needle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of an exemplary embodiment of a needle within acatheter according to the present invention;

FIG. 2 shows a detail view of the needle according to the presentinvention;

FIG. 3 a shows a side view of an exemplary embodiment of a needleaccording to the present invention;

FIG. 3 b shows a perspective view of the embodiment of the needle shownin FIG. 3 a;

FIG. 4 a shows a side view of a further exemplary embodiment of a needleaccording to the present invention;

FIG. 4 b shows a perspective view of the embodiment of the needle shownin FIG. 4 a;

FIG. 5 a shows a side view of another exemplary embodiment of a needleaccording to the present invention;

FIG. 5 b shows a perspective view of the embodiment of the needle shownin FIG. 5 a; and

FIG. 6 shows a perspective view of an exemplary embodiment of a systemaccording to the present invention.

DETAILED DESCRIPTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare referred to with the same reference numerals. Although the presentinvention is described herein in reference to sclerotherapy, thoseskilled in the art will understand that a flexible needle constructed inaccord with the present invention may be employed in any procedure whichrequires a needle with enhanced flexibility (e.g., for bending around atight radius). Furthermore, although the present invention is describedherein with specific reference to needles, those skilled in the art willunderstand that the teachings of the invention may be applied in thesame manner to a wide range of items formed of rigid materials which areinserted through endoscopes. For example, hemaclips, Enteryx® needles,fine needles, aspiration needles, and coring needles for tissueacquisition may be made more flexible using the same processes describedherein for the needle 35. Further, all gastrointestinal instruments andother medical instruments which are often formed of rigid materials toachieve a desired column strength but which are required to pass througha tortuous path to reach target tissue may be made more flexible usingthe teachings of the present invention.

As shown in FIG. 1, a catheter 5 includes an outer sheath 10 and aninner sheath 15. Both the inner sheath 15 and the outer sheath 10 may,for example, be formed of a plastic polymer tubing, although othermaterials having similar characteristics (e.g., flexibility,biocompatibility, etc.) may be used. A needle 35 is attached to innersheath 15 by, for example, mechanically crimping a proximal end of theneedle 35 to a distal end of the inner sheath 15. Alternatively oradditionally, an adhesive 18 may be applied to the proximal end of theneedle 35 to bond it to the inner sheath 15. A first predeterminedlength 32 of the needle 35 is inserted proximally into the inner sheath15 leaving a second predetermined length 34 extending distally from thedistal end of the inner sheath 15. In one embodiment, the firstpredetermined length 32 is approximately 3 to 4 mm, and the secondpredetermined length 34 is approximately 5 to 6 mm.

The inner sheath 15 is slidably received within a lumen of the outersheath 10 so that a position of the outer sheath 10 relative to theinner sheath 15 may be manipulated by a user. During insertion andretraction of the catheter 5 through an endoscope, the outer sheath 10is advanced distally relative to the inner sheath 15 until the distalend of the outer sheath 10 extends past a distal end of the needle 35 toprotect the needle 35 and the endoscope by preventing the needle 35 fromscraping, puncturing, or otherwise damaging a wall of the endoscope.

After the endoscope has been positioned in a desired location relativeto the target tissue, the outer sheath 10 and the inner sheath 15 areadvanced together to project distally from a distal end of theendoscope. The needle 35 is then exposed by withdrawing the outer sheath10 proximally. Those skilled in the art will understand thatalternatively, the needle 35 may be exposed by moving the outer sheath10 and the inner sheath 15 together to the distal end of the endoscopeand then extending the inner sheath 15 distally relative to the outersheath 10. The inner sheath 15 and the outer sheath 10 are preferablymoved relative to one another via an actuator which, during use, remainsoutside the body. The actuator may be any standard actuator, but maypreferably be a one-hand operable device, such as a spool or finger loophandle as would be understood by those skilled in the art. Once exposed,the needle 35 is inserted into the target tissue by advancing the innersheath 15 further distally. At this point, a therapeutic agent (e.g., asclerosing agent) may be injected into the target tissue.

Successful insertion of the needle 35 into the target tissue may requirethe second predetermined length 34 of the needle 35 to be at leastapproximately 3 or 10 mm. Taking into account the 2 to 5 mm of needlelength required for attachment to the inner sheath 15, a total length ofthe needle 35 is approximately 1.5 cm.

According to the present invention, a plurality of slots 20 are formedat predetermined locations on the needle 35 to enhance its flexibility.The slots 20 may preferably be formed by removing segments of thematerial comprising the needle 35 as described in more detail below. Theslots 20 may be formed along the length of the needle 35 at regularintervals or may be spaced by variable distances, thereby increasing theflexibility of selected areas while leaving others relatively rigid. Inaddition, the slots 20 may be formed around an entire circumference ofthe needle 35 to achieve a substantially equal amount of flexibility inall directions or may be formed on one side only to allow greaterflexibility in one direction than another. However, an embodiment wherethe slots 20 are formed circumferentially around the needle 35 may bepreferable to achieve a substantially flexibility which is substantiallyuniform in all directions. This increased flexibility of the needle 35facilitates navigation around tight bends in the endoscope, minimizingthe risk of the needle 35 scraping or penetrating the wall of theendoscope.

The size and spacing of the slots 20 are selected to maintain apredetermined degree of axial strength sufficient to allow the needle 35to be pushed through the turns required to navigate target pathways inthe body and to penetrate the target tissue. Those skilled in the artwill understand that the outer sheath 10 adds a degree of support to theneedle 35 when the inner sheath 15 and the outer sheath 10 are advancedtogether. Thus the flexibility of the needle 35 may be increased to alevel greater than would be feasible without the outer sheath 10.

The slots 20 in the first predetermined length 32 of the needle 35 mayalso receive the adhesive 18. The slots 20 act as a mechanical lock forthe adhesive 18 to grip and hold, thereby providing a strongerattachment to inner sheath 15. Accordingly, the inner sheath 15 may bemore securely bonded to the proximal end of a needle 35 with slots 20than it would be to a typical medical needle. The slots 20 will retainflexibility where there is no adhesive or crimp. Consequently, however,the flexibility of the needle 35 may be decreased in the firstpredetermined length 32 relative to the second predetermined length 34which is exposed. As this portion is only necessarily 2 to 5 mm inlength, its decreased flexibility should not present a problem.Alternatively, the adhesive, crimp, or other attachment means may bemade flexible, and thus even this portion of the needle 35 may beslotted so that this portion too will exhibit an increased degree offlexibility. However, those skilled in the art will understand that evenin an embodiment where the attachment means is relatively stiff, theportion at which it is coupled to the inner sheath 15 is short enough topass through even the tightest bends in a narrow lumen with relativeease.

The recommended method for creating the slots 20 is by using acomputer-controlled slot grinding technology. The grinding technologyutilizes a computer to control a length of a cut made in the needle 35.Preferably, this process is used to grind the slots 20 at apredetermined width (e.g., 0.003″ to 0.004″, which converts toapproximately 0.075 mm to 0.10 mm). This process is described in detailin U.S. Pat. No. 6,766,720 the entire disclosure of which is herebyincorporated in its entirety by reference herein.

The slots allow a rigid material to exhibit flexible characteristics ina controlled manner. That is, portions of the rigid material can beselectively ground away, thereby creating slots, which may be sized andspaced to achieve a desired degree of flexibility while other areas areleft relatively stiff or are made more or less flexible. In addition, bygrinding on one side only, the material may be made flexible in onedirection and relatively stiff in other directions. By locating slotsonly in selected areas along the axis of the needle 35, a desiredflexibility may be obtained in those preselected sections of the needle35 while maintaining rigidity in other areas of the needle 35. Thegrinding process may be performed on tubing of a relatively smalldiameter, as well as tubing of a much larger diameter. Furthermore,those skilled in the art will understand that, depending on theproperties desired for the needle 35 or other instrument being formed,slots may be formed along helical paths, or substantially parallel to alongitudinal axis of the needle 35 or other instrument. In addition, thegeometry of the slots may vary from slot to slot.

Although the computer controlled slot grinding may be used to create theslots 20 in the needle 35, other methods may be used. For example, inone embodiment, a laser may be used to make the slots 20. The laser maybe employed to cut more intricate, complex shapes with precision andminimal damage (e.g. fracture) or distortion (e.g. compression) to theneedle 35. Other methods which may be used to create the slots 20 in theneedle 35 include drilling, high pressure water cutting, photo-etching,etc. In another embodiment of the present invention, the needle 35 andthe slots 20 may be created by a molding process (e.g., injectionmolding, blow molding, etc.). That is, the needle 35 may be made of astrong and/or reinforced polymer. Thus, the slots 20 would bepositioned, sized, and shaped in accordance with a pattern defined bythe molding process.

In a preferred embodiment, the needle 35 is made of a shape-memory alloy(e.g. nitinol hypodermic tubing) or of a similar material that has ahigh tensile strength. The high tensile grade of nitinol makes this typeof needle 35 easier to work with than one composed of other materials,because nitinol can withstand high amounts of flexing without fractureor permanent flexion under normal working conditions. Although nitinolis the preferred material for composition of the needle 35, othermaterials are suitable and compatible with the computer controlledgrinding process. For example the grinding process may be performed onstiff polymers (e.g. plastic polyimids), reinforced materials, stainlesssteel braided reinforced tubing, etc.

As would be understood by those skilled in the art, the flexibility ofthe needle 35 may be manipulated through variation of the shape andposition of the slots 20. FIG. 2 depicts a pattern formed by grinding aplurality of slots 20 along the needle 35, thereby excising partialcircumferential sections of the needle 35. These partiallycircumferential excisions are placed at predetermined intervals alongthe length of the needle in such a way as to increase flexibility whilemaintaining a high degree of strength. Regarding FIG. 2, narrowcircumferential sections 55 are removed from the needle 35 so that asegment 50 is left intact to keep the distal end of the needle 35 frombeing completely severed from the proximal end. In the adjacent excision60, the segment left intact is located approximately directly oppositethe original remaining segment 50 with respect to a longitudinal axis ofthe needle 35. The next adjacent partial circumferential excision 65 ispositioned such that the remaining segment 70 is roughly even with theoriginal remaining segment 50, but slightly vertically displacedtherefrom. As shown in FIG. 2, a pattern is formed in the needle 35 bythe slots 20 such that the remaining segments are substantially evenlydistributed along the axis and wrapping around the body of the needle35, along a substantially helical path. This pattern produces a degreeof flexure that is suitable for navigating through an endoscope and abody lumen and which is substantially equal in all directions.

The slots 20 as described above with respect to FIGS. 1 and 2 mayoptionally penetrate all the way to the bore 22 of the needle 35.Alternatively, the depth of the slots 20 may be less than a thickness ofa wall of a hollow needle 35. When the depth of the slots 20 is lessthan a thickness of the wall of the needle 35, the wall of the needle 35is substantially thinned at the slots 20 relative to other sections ofthe needle 35 and therefore increases a degree of flexibility of theseportions of the needle 35 while maintaining the integrity of the innerlumen of the needle 35. This allows a more precise control of thelocations at which a fluid supplied to the inner lumen of such a needle35 would be delivered. Furthermore, as the thinner section stillconnects the distal end of the needle 35 to the proximal end, such slots20 may if desired be formed fully circumferentially. This embodimenttherefore provides increased flexibility without creating porosity inthe needle 35. Those skilled in the art will understand that the depthof the slots may be varied along the length of the needle 35 to achieveany desired flexibility and/or fluid delivery characteristics along thelength of the needle 35.

As illustrated in FIG. 2, the slots are created in a substantiallyrectangular shape that extends over a substantial portion of thecircumference of the needle 35. However, the slots may take alternativeforms (e.g. elliptical, polygonal, etc.) and may be sized to extend overvarying portions of the circumference of the needle 35. Variations inthe size or shape of the slots may have a corresponding effect on theflexibility of the needle 35.

As the size and shape of the slots 20 may affect the flexibilitycharacteristics of a needle 35, the placement and separation between theslots 20 may also have a substantial effect. For instance, a pluralityof slots 20 concentrated in one portion of the needle 35 maysubstantially increase the flexibility of the needle 35 in that portion.However, that portion of the needle 35 will also lose a degree oflongitudinal rigidity. Conversely, if the same number of slots 20 arepositioned at a greater distance from one another along a longer sectionof the needle 35. However, the entire needle 35 will have a level offlexibility higher than that of the areas of this needle 35 outside thearea of dense slot concentration. The needle 35 will not have anysection as flexible as the area of dense slot concentration describedabove.

The slots 20 illustrated in FIGS. 1 and 2 are positioned in planessubstantially perpendicular with respect to the longitudinal axis of theneedle 35. In an alternative embodiment, the slots 20 may extend inplanes orientated at various angles with respect to the longitudinalaxis. A preferred range of angles with respect to the longitudinal axisof the needle 35 may be between approximately 45° and 90°.

Referring back to FIG. 1, the needle 35 has a distal tip 30 whichfacilitates penetration into target tissue. The needle 35 also includesa hollow bore 22, through which a fluid may pass proximally or distally.In sclerotherapy, for example, fluid exits the needle 35 at an outletnear the tip 30. Accordingly, once the needle 35 has been inserted intotarget tissue, an agent is injected thereinto from the distal end of theneedle 35. Due to the nature of its release, the stream of injectedfluid immediately comes into contact with the portion of target areatoward which the needle 35 is pointing. From there it spreads to therest of the target tissue. An advantage of the flexible needle of thepresent invention is that fluid may also exit through the slots 20formed along the length of the needle 35, dispersing the fluid morewidely throughout the target tissue.

If it is desired to have a needle 35 which is flexible but not porous,any slots 20 which penetrate to the bore 22 may be sealed. In oneembodiment of the present invention, the slots 20 may be sealed bydipping the needle 35 in a soft polymer. The polymer preferably coversthe slots 20 without obstructing the bore 22. As a result, a needle 35sealed with a thin polymer coating and having an outlet at the distalend will possess substantially the same flexibility characteristics asthe porous needle 35 described above. In another exemplary embodiment, athin sheath may be slidably received around the needle 35, therebysealing the slots 20. As would be understood by those skilled in theart, the sheath may be formed to impart a selected degree of rigidity tothe needle 35 so that the needle 35 will retain a desired degree offlexibility.

As shown in FIGS. 3, 4, and 5, the distal end of the needle 35 may becontoured to take a form most suitable for a desired application. FIG. 3depicts a needle 82 having a regular medical point, or a “lancet point.”The distal end of the needle 82 is shaped to form a sharp point 90. Asshown in FIG. 3, a sharp cutting edge 85 is formed at an angle (e.g.approximately 15 degrees) with respect to a longitudinal axis of theneedle 82. Preferably, the angle of the sharp cutting edge 85 may beapproximately equivalent to a diameter of the needle 35 divided by alength of the sharp cutting edge 85. The sharp cutting edge 85 meets aheel 80 of the lancet point. The heel 80 may be formed at an angle, withrespect to the longitudinal axis of the needle 35, that is smaller thanthe angle formed by the sharp cutting edge 85 as per standard needlespecifications in the industry.

FIG. 4 depicts a needle 102 having a deflected point 105 reducingpossibility of puncturing a lumen wall of an endoscope as the needle 102is advanced therethrough. The deflected point 105 also aids in keepingthe bore 110 of the needle 102 unobstructed. For example, when injectinga lancet point needle 82 such as that shown in FIG. 3 into targettissue, the large diameter of the outlet in connection with the sharpcutting edge 85 may cause a section of tissue approximately the diameterof the needle 82 to be removed. The removed tissue section may thenbecome lodged in the needle bore 95 leaving a hole in the target tissue.The deflection of the point 105 in FIG. 4 displaces the point 105 towardthe sharp cutting edge 100. Accordingly, the outlet of the hollow bore110 is more closely aligned with the longitudinal shape of the needle102. As the point 105 lies nearly on the same plane as an oppositesurface of the needle 102, and the sharp cutting edge 100 does notdirectly abut a surface of the target tissue, the needle 102 penetratestissue more smoothly. The diameter of the hole created in the tissue bythe puncture gradually increases to the diameter of the needle 102 asthe needle 102 is inserted without removing a section of tissue. Thus,the hole will close and the tissue will heal more readily.

FIG. 5 portrays a needle 122 with a deflected guide tip 125. This needle122 retains all the benefits of the needle 102 of FIG. 4. For example,the outlet of a hollow bore 130 is more closely aligned with alongitudinal shape of the needle 122, and therefore a sharp cutting edge120 does not directly abut a surface of the target tissue, enablingsmooth penetration of the needle 122. Additionally, the tip 125 of thisneedle 122 is curved towards axis of the needle 122 reducing risk ofdamaging the lumen wall as the needle 122 is passed through theendoscope.

In an alternative embodiment shown in FIG. 6, an injection catheter 5 isslid through the working channel 165 of an endoscope 170 which may be,for example, a standard endoscope including, for example, devices suchas an irrigation system 164 and at least one optical system 162 tofacilitate insertion of the endoscope 170, positioning, and performanceof the procedure. The endoscope 170 may be a single use endoscope or aconventional multi-use endoscope. The endoscope 170 is placed within abody lumen (e.g., through a naturally occurring orifice) and positionedproximate to a target area. The optical system 162, the irrigationsystem 164, and a syringe 175 are connected to the endoscope 170 througha medical luer adaptor 180, as would be understood by those skilled inthe art. The injection catheter 5 includes a needle 35 attached to aninner sheath 15, within an outer sheath 10. As with conventionalsclerotherapy needles, the needle 35 is extended and retracted asnecessary via a manipulator 185 located at the proximal end of theendoscope 170. The manipulator 185 may be a one-hand or two-handoperable device. Additionally or alternatively, the manipulator 185 maybe automatic and/or computer controlled. When in the retracted position,the needle 35 is housed within the outer sheath 10. As the needle 35 isextended and exposed from the distal end of the outer sheath 10, theuser may insert the needle 35 into the target tissue and inject fluidfrom syringe 175 into the target tissue. After the fluid has beenadministered to the target tissue, the needle 35 is retracted andwithdrawn through the endoscope 170.

In another exemplary embodiment of the present invention, the needle 35and/or the injection catheter 5 may be part of the endoscope 170. Thatis, the needle 35 and/or the injection catheter 5 may be a permanentfixture of the endoscope 170. This embodiment may be practical withrespect to incorporating the present invention into a single-useendoscope.

In another exemplary embodiment of the present invention, the needle 35may be part of an endoscopic accessory. For example, the needle 35 maybe part of a cup attached to a distal end of an endoscope (e.g., via asnap-on linkage) with a generic device connection linking the needle 35to an actuator or controller of the endoscope. For example, the needle35 may be connected to a control wire extending between a distal end ofthe endoscope and a proximal actuator of the endoscope.

The present invention has been described with reference to specificexemplary embodiments. Those skilled in the art will understand thatchanges may be made in details, particularly in matters of shape, size,material and arrangement of parts without departing from the teaching ofthe invention. Accordingly, various modifications and changes may bemade to the embodiments without departing from the broadest scope of theinvention as set forth in the claims that follow. The specifications anddrawings are, therefore, to be regarded in an illustrative rather than arestrictive sense.

1. An endoscopic instrument comprising: a first flexible insertionmember sized for insertion through a body lumen to a target site; and aneedle coupled to the insertion member for penetration of tissue, theneedle including a plurality of flexibility enhancing grooves formedtherein along at least a first portion of the length of the needle. 2.The instrument of claim 1, wherein the needle includes a bore extendingaxially therethrough, at least a first one of the grooves penetratingfrom an outer surface of the needle to the bore.
 3. The instrument ofclaim 1, wherein the grooves are formed in a plane substantiallyperpendicular to a longitudinal axis of the needle.
 4. The instrument ofclaim 1, wherein each of the grooves extends around only part of acircumference of the needle.
 5. The instrument of claim 4, wherein thepartially circumferential grooves are arranged so that midpoints of thegrooves extend along a substantially helical path.
 6. The instrument ofclaim 1, wherein the grooves are positioned substantially equidistantfrom one another.
 7. The instrument of claim 1, wherein a spacingbetween the grooves varies along the length of the first portion.
 8. Theinstrument of claim 1, wherein the first insertion member is sized to beinserted through a working channel of an endoscope.
 9. The instrument ofclaim 1, further comprising a second flexible insertion member, thefirst insertion member being slidably received within the secondinsertion member.
 10. The instrument of claim 2, wherein the boreextends to a distal opening for the injection of fluids to penetratedtissue, fluids also being supplied to tissue via the first groove. 11.The instrument of claim 1, the first insertion member being formed of afirst material and the needle being formed of a second material morerigid than the first material.
 12. The instrument of claim 1, furtherincluding a non-porous coating covering the first portion of the lengthof the needle.
 13. A method of forming a needle for use in endoscopicprocedures comprising: fabricating a needle of a material having a firststiffness; forming a plurality of grooves in at least a first portion ofthe needle to increase the flexibility of the first portion.
 14. Themethod of claim 13, wherein at least a first one of the groovespenetrates from an outer surface of the needle to a bore extendingaxially therethrough.
 15. The method of claim 13, wherein the groovesare formed in a plane substantially perpendicular to a longitudinal axisof the needle.
 16. The method of claim 13, wherein each of the groovesextends around only part of a circumference of the needle.
 17. Themethod of claim 16, wherein the partially circumferential grooves arearranged so that midpoints of the grooves extend around the needle alonga substantially helical path.
 18. The method of claim 13, wherein thegrooves are positioned substantially equidistant from one another. 19.The method of claim 13, wherein a spacing between the grooves variesalong the length of the first portion.
 20. The method of claim 13,further comprising applying a non-porous coating to the first portion ofthe needle.